Add word wrapping option

[tsenart]

Fixes #66 and supplants #88.

[YellowAfterlife]

This adds a wrap option but does not modify layout (line number column) to not break line number display on wrap (see sample from original issue).

[tsenart]

Would you please post an image showing the difference?

[YellowAfterlife]

With my PR:

With this PR:

Most of the odd-ish code in my PR is to switch the highlighter to generate tables instead to workaround this issue.

[tsenart]

OK, is there a pure CSS way to achieve this?

[YellowAfterlife]

As far as I understand, it would not be possible without changing something in the existing structure, since currently the lines are not even explicitly wrapped in any particular element, meaning that you cannot measure their height or apply selectors to them.

The simplest solution would probably be this, which has each line wrapped in a <span> (instead of having a blank <span> before the line contents) to be able to give it padding-left and stick a ::before pseudoelement into that area. Note that this would not automatically resize all line counter elements to fit required width, however, so additional rules might be required to make the line number area wider if there are more than 100, 1000, etc. lines in the output.

[tsenart]

@YellowAfterlife: I like that direction a lot more. Would be happy to review a patch on top of this PR to fix the issue.

[YellowAfterlife]

YAL-Forks@8fa28b4
I don't truly like the line-digits-# part but that's the best it gets without giving every line-node a width property explicitly or rewriting everything to use tables.
Had only come to realization that the whole thing with line-numbers is a hack on top of hljs and there was no use in my previous attempt of implementing them without modifying hljs.js.

[tsenart]

I don't really want to maintain a fork of the HLJS library so the solution needs to build on top of its quirks.

[YellowAfterlife]

Well, you already do, for two years now. Would you want a PR that updates hljs to current version and adds tweaks for line numbers (probably by making a wrapper .js for both background.js and options.js to use) without modifying hljs then?

[tsenart]

@YellowAfterlife: Oh, wow. Memory runs short indeed. Thanks for spotting that. So, yes I'd very much appreciate that contribution. Thank you!